Polymers containing furyl functionality either at the chain end(s) or as pendant groups are of great interest in view of the demonstrated capability of the furyl moiety to participate in Diels-Alder reaction with suitable dienophiles which offers possibilities for their chemical modifications. Polymers possessing furyl groups at the chain ends have been synthesized either via chain polymerization by making use of furyl group-containing initiators, or by end group modification of prepolymers obtained via step growth polymerization with furyl containing reagents such as furfuryl amine or furfuryl alcohol. Polymers containing pendant furyl groups have been synthesized by the chain polymerization of addition monomers or by step growth polymerization of condensation monomers containing furyl groups. Chemical modification approach has also been employed to synthesize polymers with pendant furyl groups.
Polymers containing pendant furyl groups are of particular interest as they can undergo Diels-Alder reaction with suitable dienophiles such as bismaleimides resulting into the formation of crosslinked materials exhibiting thermoreversible characteristics and self-healing ability.
Article titled “Photosensitive poly(urethane acylsemicarbazide)s with azobenzene chromophores in the main chain” by A Palanisamy et al. published in Journal of Applied Polymer Science, 2004, 93 (1), pp 444-454 reports synthesis of poly(urethane acylsemicarbazide)s in a two-step process: (1) the in situ generation of diisocyanate through the thermal decomposition of an azobenzene-containing precursor diacyl azide and a reaction with ester/ether polyols to form an isocyanate-terminated prepolymer and (2) chain extension in N,N-dimethylacetamide with aliphatic or aromatic diacyl hydrazides.
Article titled “Diels-Alder-based crosslinked self-healing polyurethane/urea from polymeric methylene diphenyl diisocyanate” by P Du et al. published in Journal of Applied Polymer Science, 2014, 131 (9), pp 40234 reports synthesis of crosslinked self-healing polyurethane/urea based on a Diels-Alder reaction from a multiple-furan monomer and a commercial bismaleimide.
Article titled “Thermally reversible cross-linked poly(ether-urethane)s” by C Gaina et al published in Express Polymer Letters, 2013, 7 (7), pp 636-650 reports the synthesis of furan-containing poly(ether-urethane)s by the polyaddition reaction of 1,6-hexamethylene diisocyanate (HMDI) or 4,4′- dibenzyl diisocyanate (DBDI) to poly(tetramethylene ether) glycol and 2-[N,N-bis(2-methyl-2-hydroxyethyl)amino]furfuryl as chain extender by the solution prepolymer method.
Most of the reports pertaining to difunctional monomers containing pendant furyl group deal with aliphatic monomers. Thus, there is a need of aromatic difunctional monomers containing pendant furyl group which are useful for the preparation of polyurethanes, polyureas and high performance polymers viz., aromatic polyimides, aromatic polyamides, aromatic polyesters, aromatic polyhydrazides etc.